Electrostatic precipitator



E 1957 M. ROBERTS 2,800,192

' ELECTROSTATIC PRECIPITATOR' Filed Oct. 10, 1955 INVENTOR LAWRENCE M.ROBERTS ATTORNEY United States PatentQ ELECTROSTATIC PRECIPITATORLawrence M. Roberts, Bound Brook, N. J., assignor to ResearchCorporation, New York, N. Y., a corporation of New York ApplicationOctober 10, 1955, Serial No. 539,510

3 Claims. (Cl. 183-7) This invention relates to new and improvedapparatus for electrostatically removing suspended particulate materialfrom gas streams and more particularly to electrostatic precipitatorscomprising at least 'two vertically superposed precipitation sections.

It is a principal object of the present invention to provide electricalprecipitation apparatus comprising at least two vertically superposedprecipitation sections permitting substantial savings in theconstruction of the shell, hopper, flue, piping and valves and in thespace requirements of the assembled unit.

t A further object is to provide such a device having liquid flushedcollecting electrodes wherein the flushing liquid supplied to theuppermost section of the electrostatic precipitator is collected anddistributed to the electrical precipitation section therebelow.

A further object of the invention is to provide such a device whereinthe gas stream treated in the lowermost section is collected andredistributed to the uppermost sections providing uniform gasdistribution and uniform particle redistribution in the gas stream to betreated in the subsequent gas treating sections.

These and other objects and advantages are provided by the apparatus ofthe present invention which generally comprises a housing, a walldividing the housing into an upper and lower gas treating chamber, thedividing wall being secured to the inner vertical surface of the housingand sloping generally upwardly therefrom, a first horizontal headersheet in the lower gas treating chamber, a second horizontal headersheet in the upper gas treating chamber, a plurality of collectingelectrode openings in the first and second header sheets, a tubularelectrode secured in each of the openings in the first and second headersheets, the header sheets forming with their respective tubularelectrodes flushing ponds, a discharge electrode extending through eachof the collecting electrodes, dirty gas inlet means below the firstheader sheet, clean gas outlet means above the second header sheet,means conducting gas from the lower gas treating chamber to the uppergas treating chamber said means including a conduit extending upwardlyfrom the dividing wall to a position between the tubular collectingelectrodes below the second header sheet and drain means connecting theupper surface of the dividing wall and the upper surface of the firstheader sheet.

The invention will be more particularly described with reference to theillustrated embodiments of the invention wherein:

Fig. 1 is a vertical view in partial section of an electrostaticprecipitator constructed in accordance with the principles of thepresent invention and Fig. 2 is a section substantially on line 22 ofFig. 1.

- from the gas stream to be cleaned from the shell of the Referring tothe drawings, 10 generally designates the I Below the dividing wall 22is provided a header or tube,

sheet 24 provided with a plurality of openings therethrough into whichare fitted a plurality of tubular extended surface collecting electrodes26. The upper ,ends of the tubular collecting electrodes 26 projectabove the header sheet 24 and cooperate with the header sheet to provideponds for electrode flushing liquids as is well known in the art.

Centrally disposed within each of the collecting electrodes 26 is adischarge electrode 28 suspended from bus bars 30 supported byinsulators in insulator housing 31, and connected to a source of highvoltage. The lower ends of the discharge electrodes 28 are secured to as'teadying frame 32.

Gas treating section B, positioned vertically above gas treating sectionA, includes a header or tube sheet 34 provided with a plurality ofopenings therethrough into each which is secured a tubular extendedsurface collecting electrode '36. The upper ends of each collectingelectrode 36 projects above the upper surface of the tube sheet 34 toprovide for liquid ponds as defined by the collecting electrodes, thetube sheet 34 and radial partition members 38. The radial partitionmembers 38 divide the collecting electrodes into groups whereby evenflow of flushing liquid may be provided for the electrodes without thenecessity of leveling each electrode in the entire section relative toeach other.

Centrally positioned within each of the collecting electrodes 36 is adischarge electrode 40 supported at its upper end by bus bars 42suspended from rods 44 connected to insulators in insulator housings 48.The lower ends of the discharge electrodes 40 are attached to steadyingframes generally indicated at 50. Above the bus bars 42 are provided aplurality of conduits 52 having depending spray heads 54'secured theretoto provide a liquid spray for maintaining pools of liquid in the liquidponds and for cleaning the discharge electrodes and associated hightension frames of deposited material. Conduits 56 are also provided inthe upper section of the precipitator above the upper surface of tubesheet 34 for directing flushing liquid into the plurality of ponds;there being at least one conduit 56 for each of the plurality of ponds.

The tube sheet '24 of precipitator section A and the dividing wall 22are divided into segments by members 60 and 62 respectively positionedvertically below the members 38 forming the plurality of ponds in theupper precipitator section B. Each 'ofthe areas formed by par? titionmembers 62 and thedividing wall 22 are connected to the ponds formed bymembers 60 and header sheet 24 by conduits 64, which are shown in thedisclosed form of the invention as terminating slightly above the uppersurface of tube sheet 24 but below the level of the liquid in theflushing ponds of section A whereby gas passing through the tubularcollecting electrodes 26 will be prevented from flowing upwardly throughthe drain pipes 64.

In order to direct the gas stream being cleaned, after passing throughthe lowermost section A, to the second section B of the precipitator aconduit generally designated 66 extends from the lower surface of thedividing wall 22 upwardly between the collecting pipes 36 ofprecipitator section B to discharge the gas above the lower ends of thecollecting electrodes and below tube sheet 34.

In operation of the apparatus of the invention gases to be cleanedcontaining suspended particulate material enter the precipitationchamber A through dirty gas inlets 68 opening through the wall of thehousing slightly below the header sheet 24. The gases fiow downwardly tothe open ends of collecting electrode tubes 26 and pass upwardlytherethrough where a portion of the particulate material suspended inthe gas stream is electrostati cally precipitated upon the innersurfaces of the tubes. The gases issuing from the upper ends of thecollecting electrode tubes 26 collects above the tubes and flowsupwardly through conduit 66 and out into the space about the collectingelectrodes 36 of precipitator section B where the gas again flowsdownwardly to the open ends of tubes 36 and upwardly therethrough. Itwill be noted that the gas issuing from the collecting electrode tubesof section A is remixed 'and'distributed to the collecting tubeelectrodes of section B in the space between the upper surface of headersheet 24 and lower surface of the dividing wall 22 and in the restrictedconduit 66. The gases after passing through the second'section of theelectrostatic precipitator issue as clean gases from the precipitatoroutlet 16.

Particulate material from the gas stream deposited upon the dischargeelectrodes and their supporting frame are washed therefrom by liquidissuing from spray 54 while the particulate material precipitated on theinner surfaces of the tubular collecting electrode 36 are flushedtherefrom by liquid directed to the ponds by pipes or conduits 56. Theliquid from the ponds and the sprays 54 containing the removedparticulate material flows from the lower ends of the collecting anddischarge electrodes of section B to the upper surface of the dividingwall 22 where the liquid flows through drain pipes 64 to provideflushing liquid for the collecting electrodes 26 of section A. Spraymeans 70 similar to the sprays 54 of section B are provided in section Ato maintain the discharge electrodes and their supporting frame free ofdeposit of particulate material. The flushing liquid containing theparticulate material from both sections A and B collect in the lower end18 of the casing 10 andare drained therefrom through suitable meansconnected to outlet 20.

From the foregoing discussion it will be seen that the flushing liquidfor the tubular collecting electrodes 36 of section B is reused toprovide the flushing liquid for the collecting electrodes 26 of sectionA thereby substantially reducing the cost of flushing liquid andincreasing the concentration of the particulate material in the liquidcollected at the lower end of the precipitator.

In general flushing liquid required for each pipe in an electrostaticprecipitator having a diameter of about 12 inches is about 1 gallon perminute. It is therefore seen that on electrostatic precipitators of thetype disclosed in the present inventionhaving, for example, 300electrodes in each section A and B the saving in flushing liquid aloneis about 300 gallons per minute.

'From the foregoing description it will be seen that the precipitator ofthe present invention fully accomplishes the aims and objectshereinbefore set forth. It will also be apparent that the embodimentsshown are only exemplary of a particular form of the apparatus forcollecting suspended particles in gas streams and that variousmodifications can be made in the construction and arrangement of theelements thereof without departing from the scope of the presentinvention.

I claim:

1. An electrostatic precipitator comprising a housing, a wall dividingthe housing into upper and lower gas treating chambers, said wall beingsecured to the inner vertical surface of the housing and slopinggenerally upwardly therefrom, a first horizontal header sheet in thelower gas treating chamber, a second horizontal header sheet in theupper gas treating chamber, a plurality of collecting electrode openingsin the first and second header sheets, a tubular electrode secured ineach of the openings in the first and second header sheets, the headersheets forming with their respective tubular electrodes flushing ponds,a discharge electrode extending through each of the collectingelectrodes, dirty gas inlet means below said first header sheet, cleangas outlet means above the second header sheet, means for conducting gasfrom the lower gas chamber to the upper chamber, said means comprising aconduit extending upwardly from the dividing wall to a position betweenthe tubular collecting electrodes below the second header sheet, conduitmeans for providing flushing liquid forthe ponds associated with theupper header sheet and drain means connecting the upper surface of thedividing wall and the upper surface of the first header sheet to provideliquid for the flushing ponds of said lower gas'treating chamber.

2. The apparatus defined in claim 1 wherein division strips extendingvertically upwardly from the upper surface ofthe' first and secondheader sheets and the dividing wall divide said'members into a pluralityof segmental units.

3. An electrostatic precipitator comprising a housing having generallyhorizontal extending partition means secured, to the inner verticalsurface of the housing and sloping generally upwardly therefrom toprovide a plurality of verticallysuperposed gas-treating chambers, eachof said chambers having a transverse header plate with tubularcollecting electrodes disposed in openings in said header plate todepend therefrom and to extend above said header plate 'to form aflushing liquid pond thereabove, a discharge electrode extending througheach collecting electrode, gas inlet'means below the header plate of thelowermost chamber, gas outlet means above the header plate of theuppermost chamber, conduit means extending upwardly from each of thepartition means to a position between the tubular collecting electrodesin the chamber thereabove to conduct gas from each lower chamber to aposition between the collecting electrodes and below the header plate ofa superposed chamber, conduit means for supplying flush liquid to thepond above the uppermost chamber and drain means for conducting flushingliquid collected at the bottom of an upper chamber to the pond above theheader plate of a lower chamber.

References Cited in the file of this patent UNITED STATES PATENTS185,900 Ellerhorst Jan. 2, 1877 1,613,352 Kobernik Jan. 4, 19272,027,615 Prutzman Jan. 14, 1936 2,443,780 7 Wintermute June 22, 19482,701,028' 'Eilenberger Feb. 1, 1955

